ST6Gal-I Regulates Human Choriocarcinoma JAR Cells Migration Via Up-regulating A2,6-sialylation Of Integrin B1

Choriocarcinoma is a highly malignant placental the outerchoriocarcinoma cells (i.e. trophoblastic) tumors with highly invasioncapacity and metastatic ability. Recently researches of metastatic tumorsfocus gradually on protein post-translational modification (glycosylation,phosphorylation, sulfation, etc.), and glycosylation of protein is the mostcomplex and changeable, which is relative to the metastasis of malignanttumor. The different structure of oligosaccharides of glycoprotein is theresult of the activity of glycosyltransferases and glycosidases. β-galactosideα2,6-sialyltransferase-1(ST6Gal-I) can transfer sialic acid from CMP-Sia togalactose residues, and produces the Sia-α2,6-Gal linkage, which is found inmost N-linked oligosaccharide of glycoproteins as theSia-α2,6Galβ1,4GlcNAc-R. The α2,6-sialylation of ST6Gal-I substrates caneffect their structure and activity, which involve a series of cell immigration,adhesion proliferation and apoptosis. It has been reported that up-regulatedST6Gal-I often correlates with human cancer (glioma, ovarian cancer, coloncancer, etc.) metastatic spread. Therefore, it is important to explore therelationship of glycoprotein on the tumor cell membrane and its metastasisactivity, so we can reveal the mechanism of tumor metastasis in clinical andfind new molecular markers.In this study, the objects were human chorionic carcinoma cell lines JAR and human normal extravillous trophoblastic HTR-8/Svneo. Toinvestigate the molecular mechanism of regulation of ST6Gal-I on themigration of JAR cell, quantitative-PCR, western blot, siRNA interference,transwell method were used to detect the expression leves of ST6Gal-ImRNA, protein and α2,6-sialylated protein in these both cell lines. Theresults of this study were as follows:1. The cellular morphology of these two cells is obviously different.HTR-8/SVneo cells are fusiform and growth stretching，but JAR cells arepolysynaptic and growth into the group.2. JAR cells migration ability was stronger than HTR-8/SVneo cells viatranswell assay.3. Detected by PCR, Western Blot and Lectin Blot the expression levelsof ST6Gal-I mRNA and protein and α2,6-sialylated total protein in JARcells were higher than HTR-8/Svneo cells, which was correlative with theirmigration ability.4. Down-regulation of ST6Gal-I in JAR cells by siRNA interferencetechnology diminished the capacity of cell migration, and the sialylation ofintegrin β1was down regulated too by Immunoprecipitation.5. The active form of FAK, ERK protein which was significantly downregulated by western blot, and after the treatment of phosphorylated ERKinhibitor the expression of ST6Gal-I and sialylated total protein wasdown-regulated.In summary, the migration of human choriocarcinoma cell (JAR) isstronger than normal human extravillous trophoblast cell (HTR-8/Svneo), itmay be related to the difference of ST6Gal-I protein expression in these twocell lines. ST6Gal-I through the up-regulation of sialylated-integrin β1,FAK-ERK signaling pathway promores choriocarcinoma cell migration, while ERK can regulate the expression of ST6Gal-I. These results areimportant to discovery the new therapeutic targets of choriocarcinoma. Themechanism of regulation of ST6Gal-I on cell migration in choriocarcinomamay helpful for the discovery of new therapeutic targets in clinic.